In semiconductor manufacturing steps, various processes to a thin disk-like wafer to form a plurality of chips (dies) each having an electric device. Each of the chips are inspected with respect to electric characteristics. Thereafter, the chips are cut off by a dicer, and each of the chips is fixed on a lead frame or the like and assembled as an electronic device. The inspection of electric characteristics is performed by a probe card and a tester. The wafer is fixed to a chuck on a stage, and probes are brought into contact with the pads of the chips. The tester supplies an electric power and various test signals from terminals connected to the probes, and the tester analyzes signals output to the pads of the chips to check whether the chips normally operate (for example, see Patent Literature 1).
An electronic device has a wide array of uses, and is used in a wide temperature range. For this reason, when a wafer on electronic devices are disposed is to be inspected, for example, the inspection must be performed at a high temperature at which a wafer placed on a chuck has a temperature of 200° C. and at a low temperature at which the wafer has a temperature of −55° C.
A plurality of chips are disposed in lines on a wafer, and a plurality of pads are disposed on the chips, respectively. The shapes of the pads may be square shapes, pentagonal shapes, octagonal shapes, polygonal shapes, circular shapes, or the like. The surfaces of the pads may be plain surfaces, striped-pattern surfaces, geometrical-pattern surfaces, or the like. The materials of the pads may be aluminum, gold, solder bumps, and the like.
When each of the chips is to be electrically inspected, the inspection is performed such that a plurality of probes disposed on a probe card to correspond to a plurality of pads formed on each chip are simultaneously brought into contact with the pads, respectively. For this reason, before the electrical inspection is started, on the basis of the pad information, a position of the pad on each of the chips disposed on the wafer must be recorded. In the wafer inspection, positions of the pads on the wafer and positions of the probes are calculated on the basis of position information of the pads on each of the chips, and each of the probes must be reliably brought into contact with the center of each of the pads.
In the registration of the pad position, an operator moves one chip with respect to a microscope or a camera (to be generically referred to as a camera hereinafter) to monitor the pad in a video image on the camera and to record the position of the pad on a control unit. In the control unit, pad position information of each wafer type is created on the basis of the recorded data, correction calculation with respect to the probe positions on the probe card is performed on the basis of the pad position information, and the inspection is performed after the position correction is performed. Note that, as an operation time required to register the positions of the pads, an operation time of about 2 to 3 seconds is required for one pad of one chip at present. Thus, an operation time required for registration of all the pads of one chip is obtained by multiplying the number of registered pads by the operation time (2 to 3 seconds) per pad. When the number of pads increases, the operation time increases.